from jet scaling to jet vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf ·...
TRANSCRIPT
![Page 1: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/1.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
From Jet Scaling to Jet Vetos
Tilman Plehn
Heidelberg
ATLAS Higgs-Tau Workshop, 3/2012
![Page 2: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/2.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
![Page 3: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/3.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
Why not [intro: arXiv:0910.4182, Springer Lecture Notes]
– remember qg → qZ
– collinear divergence from g → qq splitting [overlapping with soft divergence]Z pmaxT
pminT
dp2T
Cp2
T
= 2Z pmax
T
pminT
dpT pTCp2
T
' 2CZ pmax
T
pminT
dpT1
pT= 2C log
pmaxT
pminT
universal form following factorization
σn+1 =
Zσn
dp2a
p2a
dzαs
2πP(z)
– universally divergent, fixed order poorly defined
⇒ find object to ‘renormalize’ [i.e. absorbe universal divergence]
![Page 4: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/4.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
DGLAP equation and jet-inclusive rates
– re-organize perturbation series [sum collinear logs]
σn+1(x, µ) ∼1n!
1
2πb0log
αs(µ20)
αs(µ2)
!n Z 1
x0
dxn
xnP„
xxn
«· · ·Z 1
x0
dx1
x1P„
x2
x1
«σ1(x1, µ0)
– DGLAP equivalent to ‘infrared RGE’
– factorization scale as inclusive momentum cutoff [vanishing at all orders]
σtot(µ) =
Z 1
0dx1
Z 1
0dx2
Xij
fi (x1, µ) fj (x2, µ) σij (x1x2S, µ)
⇒ collinear jets automatically included [veto on hard jets ok only if pmaxT ,j > hard scale]
![Page 5: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/5.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet counting
Why count jets
– complete event reconstruction crucial at LHC [Higgs plus 0,1,2 jets; jets plus /~pT ]
– utilize tagging and recoil jets in Higgs searches
– reduce t t and gg backgrounds
– identify decay jets in BSM searches
⇒ dσ/dnjets just another distribution to cut on?
DGLAP equation and jet-inclusive rates
– re-organize perturbation series [sum collinear logs]
σn+1(x, µ) ∼1n!
1
2πb0log
αs(µ20)
αs(µ2)
!n Z 1
x0
dxn
xnP„
xxn
«· · ·Z 1
x0
dx1
x1P„
x2
x1
«σ1(x1, µ0)
– DGLAP equivalent to ‘infrared RGE’
– factorization scale as inclusive momentum cutoff [vanishing at all orders]
σtot(µ) =
Z 1
0dx1
Z 1
0dx2
Xij
fi (x1, µ) fj (x2, µ) σij (x1x2S, µ)
⇒ collinear jets automatically included [veto on hard jets ok only if pmaxT ,j > hard scale]
⇒ but still...
![Page 6: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/6.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Poisson scaling
Theory: soft gluon radiation [Peskin & Schroeder Ch 6]
– example: photons off hard electrononly abelian diagrams, successive radiation
– eikonal approximation
Mn+1 = gsT aε∗µ(k) u(q)
qµ +O( /k)
(qk) +O(k2)Mn
– factorization of ‘hard process’ and soft radiation factors
– Poisson distribution [normalized pdf for n if n expected]
σn =nne−n
n!⇐⇒ R(n+1)/n =
σn+1
σn=
nn + 1
Basis of Poisson distribution
1– radiation matrix element nn:abelian fine, non-abelian a little tricky [ISR-FSR, see Ioffe, Fadin, Lipatov]
2– phase space factor 1/n!:only combinatorics, matrix element ordered [angular ordering, color suppression]
3– normalization factor e−n
– just like parton shower in collinear regimes
s
s
1/pT
1/pT
1/pT
![Page 7: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/7.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
![Page 8: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/8.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
![Page 9: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/9.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
![Page 10: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/10.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
– confirmed by ATLAS/CMS
![Page 11: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/11.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
– confirmed by ATLAS/CMS
Theoretical studies [Englert, TP, Schichtel, Schumann]
– CKKW/MLM merging [we used Sherpa]
– phase space effects? → moderate
– αs uncertainties? → small
– scale uncertainties? → tuning parameter?jetsn
2 3 4 5 6
jets
dndN
210
310
410
510
610
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
jetsn2 3 4 5 6
jets
dndN
210
310
410
510
610
jetsn2 3 4 5 6
var
iati
onsα
0.5
1
1.5 theoretical uncertainty
statistical uncertainty
jetsn2 3 4 5 6
var
iati
onsα
0.5
1
1.5
jetsn2 3 4 5 6
var
iati
onµ
1
10
jetsn2 3 4 5 6
var
iati
onµ
1
10
![Page 12: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/12.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Staircase scaling
Experiment: from UA1 to ATLAS/CMS [Steve Ellis, Kleiss, Stirling]
– W/Z+jets production– many equivalent descriptions
R(n+1)/n =σn+1
σn= const
– same for inclusive and exclusive rates [Blackhat-Sherpa]
R incl(n+1)/n =
P∞j=n+1 σ
(excl)j
σ(excl)n +
P∞j=n+1 σ
(excl)j
= Rexcl(n+1)/n
– confirmed by ATLAS/CMS
Theoretical studies [Englert, TP, Schichtel, Schumann]
– CKKW/MLM merging [we used Sherpa]
– phase space effects? → moderate
– αs uncertainties? → small
– scale uncertainties? → tuning parameter?
– same for QCD jets
– correctly described by ME-PS merging!?
jetsn2 3 4 5 6
jets
dndN
410
510
610
710
810
910
1010
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
QCD
µQCD, 1/4
µQCD, 4
jetsn2 3 4 5 6
jets
dndN
410
510
610
710
810
910
1010
jetsn2 3 4 5 6
var
iati
onsα 0.8
1
1.2 theoretical uncertainty
statistical uncertainty
jetsn2 3 4 5 6
var
iati
onsα 0.8
1
1.2
jetsn2 3 4 5 6
var
iati
onµ 1
10
210
jetsn2 3 4 5 6
var
iati
onµ 1
10
210
![Page 13: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/13.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Interpolating scaling patterns
Scaling for photon plus jets [Englert, TP, Schichtel, Schumann]
– naively, no scaling at all [CMS, private complaint]
– after appropriate cuts, great playground
1– staircasedemocratic γ and jet acceptancelarge γ-jet separation [m or ∆R, no large logs]
no reason for ordered emission [1/n! in Poisson form]
dominant: non-abelian splitting of ISR gluonhelping: pdf effect shifting to high-njets
2/1 3/2 4/3 5/4 6/5 7/6
nn+
1R
0
0.1
0.2
0.3
0.4
0.5
=-0.0064dndR
=0.15970R> 70 GeV, ,jγm
=-0.0007dndR
=0.14880R> 90 GeV, ,jγm
=0.0029dndR
=0.14070R>110 GeV, ,jγm
![Page 14: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/14.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Interpolating scaling patterns
Scaling for photon plus jets [Englert, TP, Schichtel, Schumann]
– naively, no scaling at all [CMS, private complaint]
– after appropriate cuts, great playground
1– staircasedemocratic γ and jet acceptancelarge γ-jet separation [m or ∆R, no large logs]
no reason for ordered emission [1/n! in Poisson form]
dominant: non-abelian splitting of ISR gluonhelping: pdf effect shifting to high-njets
2/1 3/2 4/3 5/4 6/5 7/6
nn+
1R
0
0.1
0.2
0.3
0.4
0.5
=-0.0064dndR
=0.15970R> 70 GeV, ,jγm
=-0.0007dndR
=0.14880R> 90 GeV, ,jγm
=0.0029dndR
=0.14070R>110 GeV, ,jγm
2– Poissongenerate ‘hard process’ [m, pT ,∆R, ...]
lower general pminT for soft-collinear logarithm
rely on lot-enhanced radiation
dominant: successive ordered ISRremaining: high-n staircase tail
⇒ staircase–Poisson transition tunable!
2/1 3/2 4/3 5/4 6/5 7/6 8/7n
n+1
R0
0.5
1
1.5 =1.7138n
=0.01310R>100 GeV,
T,j1p
=2.361n
=-0.05090R>150 GeV,
T,j1p
=2.6287n
=-0.05360R>200 GeV,
T,j1p
![Page 15: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/15.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
![Page 16: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/16.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
– implicit in LHC Higgs searchesindividual searches for exclusive fixed njets
– problem in Higgs phenomenology [mine for more than 10 years]
![Page 17: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/17.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
– implicit in LHC Higgs searchesindividual searches for exclusive fixed njets
– problem in Higgs phenomenology [mine for more than 10 years]
Using jet counting [Gerwick, TP, Schumann]
– avoid Pveto as single number
– study exclusive njets distribution:1– understand basic features:
staircase for inclusive samplesPoisson for radiation processes
2– predict from theory [including error]
3– validate simulation4– estimate alowed parameter range5– extrapolate to Higgs
![Page 18: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/18.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Jet veto in Higgs analyses [Barger, Phillips, Zeppenfeld; Rainwater]
– particularly useful for WBF signals [remove t t and Z+jets backgrounds]
– veto central (semi-hard) jetsestimate Pvetoapply as ‘efficiency factor’
– implicit in LHC Higgs searchesindividual searches for exclusive fixed njets
– problem in Higgs phenomenology [mine for more than 10 years]
Using jet counting [Gerwick, TP, Schumann]
– avoid Pveto as single number
– study exclusive njets distribution:1– understand basic features:
staircase for inclusive samplesPoisson for radiation processes
2– predict from theory [including error]
3– validate simulation4– estimate alowed parameter range5– extrapolate to Higgs
staircase scaling Poisson scaling
σn σ0 e−bn σtote−n nn
n!
Rexcl(n+1)/n e−b n
n + 1
Rincl(n+1)/n e−b
0@ (n + 1) e−n n−(n+1)
Γ(n + 1) − nΓ(n, n)+ 1
1A−1
〈njets〉1
2
1
cosh b − 1n
Pveto 1 − e−b e−n
![Page 19: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/19.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Example: WBF H → ττ [Gerwick, TP, Schumann]
– staircase scaling before WBF cuts [QCD and e-w processes]
– first emission sensitive to cuts
– e-w Zjj production with too many structures
1
n!/n+1!-1 0 1 2 3 4 5 6
) n!/
n+1
!R(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Higgs gluon fusion
Z QCD
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4 6/5
1
n!/n+1!-1 0 1 2 3 4 5 6
) n!/
n+1
!R(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Higgs WBF
Z EW
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4 6/5
![Page 20: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/20.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Example: WBF H → ττ [Gerwick, TP, Schumann]
– staircase scaling before WBF cuts [QCD and e-w processes]
– first emission sensitive to cuts
– e-w Zjj production with too many structures
Forward tagging jets
– count add’l veto jets to reduce backgrounds
pvetoT > 20 GeV min y1,2 < yveto
< max y1,2
– Poisson for QCD processes [‘radiation’ pattern]
1
n!/n+1!-1 0 1 2 3 4 5
) n!/
n+1
!R(
0
0.5
1
1.5
2
2.5
Higgs gluon fusion
Z QCD
n(Z QCD) = 1.42
n(Higgs gg fusion) = 1.80
0.5
1.0
1.5
2.0
2.5
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4
![Page 21: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/21.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Jet veto in Higgs searches
Example: WBF H → ττ [Gerwick, TP, Schumann]
– staircase scaling before WBF cuts [QCD and e-w processes]
– first emission sensitive to cuts
– e-w Zjj production with too many structures
Forward tagging jets
– count add’l veto jets to reduce backgrounds
pvetoT > 20 GeV min y1,2 < yveto
< max y1,2
– Poisson for QCD processes [‘radiation’ pattern]
– staircase-like for e-w processes [generic]
– features of njets distributions understood
⇒ cut on njets fine, your job now1
n!/n+1!-1 0 1 2 3 4 5
) n!/
n+1
!R(
0
0.5
1
1.5
2
2.5
Higgs gluon fusion
Z QCD
n(Z QCD) = 1.42
n(Higgs gg fusion) = 1.80
0.5
1.0
1.5
2.0
2.5
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4
1
n!/n+1!-1 0 1 2 3 4 5
) n!/
n+1
!R(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Higgs WBF
Z EW
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R(n
+1)
/n
n + 1
n
1/0 2/1 3/2 4/3 5/4
![Page 22: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/22.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
![Page 23: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/23.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriond
0
0.5
1
1.5
2
110 115 120 125 130 135 140 145 150
mH [GeV]
68% CL ATLAS+CMS
∆W∆Z∆t∆b∆
τ∆H
![Page 24: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/24.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriondend of 2012
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
110 115 120 125 130 135 140 145 150
mH [GeV]
68% CL ATLAS+CMS
∆W∆Z∆t∆b∆
τ∆H
![Page 25: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/25.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriondend of 2012assuming mH = 125 GeV
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
∆H
∆W
∆Z
∆t
∆b
∆τ
∆γ
∆g
∆Z/W
∆τ/b
∆b/W
gj = gjSM
(1+∆j)
68% CL: ATLAS + CMS
7 TeV, 20 fb-1
14 TeV, 30 fb-1
no D5
14 TeV, 30 fb-1
with D5
![Page 26: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/26.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Higgs couplings
Veto probabilities crucial for coupling extraction [SFitter: Lafaye, TP, Rauch, Zerwas (2009ff)]
– theory:Higgs portal? [φ†φ gauge singlet]
γγH and ggH couplings w/o naive decouplingSUSY or strongly interacting Higgs simple coupling measurements
– experiment:Higgs decays to fermions crucialassociated Higgs-jet channels/WBF crucial
– current observables: σ × BRmore relevant: gjjH
Dedicated parameter analysis in progress [SFitter+Duhrssen, Klute]
– general fit of all couplings [Moriond 2012]
gjjH = gSMjjH`1 + ∆j
´– prelim: SM central values, proper errors
– pre-Moriondend of 2012assuming mH = 125 GeV
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
∆H
∆W
∆Z
∆t
∆b
∆τ
∆γ
∆g
∆Z/W
∆τ/b
∆b/W
gj = gjSM
(1+∆j)
68% CL: ATLAS + CMS
7 TeV, 20 fb-1
14 TeV, 30 fb-1
no D5
14 TeV, 30 fb-1
with D5
⇒ LHC task for coming years
![Page 27: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/27.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
[GeV]effm200 400 600 800
[1/
100
GeV
]ef
fdmdN 310
410
510
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
2≥ jn
> 50 GeVT, j
p
-1L = 1 fb
W+jets
µW+jets, 1/4
µW+jets, 4
[GeV]effm200 400 600 800
[1/
100
GeV
]ef
fdmdN 310
410
510
[GeV]effm200 400 600 800
var
iati
onsα 0.9
1
1.1 theoretical uncertainty
statistical uncertainty
[GeV]effm200 400 600 800
var
iati
onsα 0.9
1
1.1
[GeV]effm200 400 600 800
var
iati
onµ
1
10
[GeV]effm200 400 600 800
var
iati
onµ
1
10
![Page 28: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/28.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
– estimate SUSY significance as function of meff
[GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510 signalleptonictt
hadronicttW+jetsZ+jetsQCD
[GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3
= 2jn
-1L = 1 fb
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3 [GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510 signalleptonictt
hadronicttW+jetsZ+jetsQCD
[GeV]effm200 400 600 800 1000 1200 1400
[1/
100
GeV
]ef
fdmdN
-210
-1101
10
210
310
410
510
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3
= 3jn
-1L = 1 fb
[GeV]effm200 400 600 800 1000 1200 1400
BS+
B
0.5
1
1.5
2
2.5
3
![Page 29: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/29.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
– estimate SUSY significance as function of meff
– multijet studies establishing meff
![Page 30: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/30.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
New physics
Effective mass [Englert, TP, Schichtel, Schumann]
– obviously sensitive to new physics massesbut awful variable, after theory uncertainty
– correlation meff ∼ 〈pT 〉 × njets
– use merged sample for meffestimate scale and αs uncertainties
– estimate SUSY significance as function of meff
– multijet studies establishing meff
Mass vs color charge
– now, significance as function of njets
– representing new physics color charge [gluino does not decay via gluon]
– exclusive 2D likelihood including all information
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, 1 inverse fb
0Σ
6Σ
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, squarks+squarks, 1 inv. fb
0Σ
4Σ
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, squarks+gluino, 1 inv. fb
0Σ
3.2Σ
2 3 4 5 6nj0.2
0.4
0.6
0.8
1.
1.2
1.4
1.6meffHTeVL
SPS1a, gluino+gluino, 1 inv. fb
0Σ
0.6Σ
![Page 31: From Jet Scaling to Jet Vetos - thphys.uni-heidelberg.deplehn/includes/talks/2012/atlas_12.pdf · From Jet Scaling to Jet Vetos Tilman Plehn Heidelberg ATLAS Higgs-Tau Workshop, 3/2012](https://reader030.vdocuments.net/reader030/viewer/2022040206/5e03280ad9e2ea2f204204e9/html5/thumbnails/31.jpg)
Jet Scaling
Tilman Plehn
Counting jets
Poisson
Staircase
Interpolating
Jet veto
Higgs couplings
New physics
Exclusive jet counting
staircase (non-abelian) vs Poisson (ordered)
– start by measuring dσ/dnjets
– test both regimes in photon+jets
– test ME-PS merging [CKKW/MLM, unchanged by NLO]
– key to jet vetos
– key to coupling measurements [SFitter+friends]
Understanding Jet Scaling and Jet Vetos in Higgs SearchesE Gerwick, TP, S SchumannPRL 108 (2012)
Establishing Jet Scaling Patterns with a PhotonC Englert, TP, P Schichtel, S SchumannarXiv:1108.5473, JHEP in print
Jets plus Missing Energy with an AutofocusC Englert, TP, P Schichtel, S SchumannPRD83 (2011)
Much of this work was funded by the BMBF Theorie-Verbund which is ideal for hard and relevant LHC work